Well, I've finally done it. My site is up with some basic info about a design that's been banging around in my head for awhile dealing with motor/wheel speed sensors.
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For practicality, this would probably need to be mounted on the motor shaft as the resolution is not as fine as a optical wheel encoder. The pulse trains connect to a couple of 16-bit timers in event capture mode to count the pulses within a specific time frame.
Why do it like this? So the MCU can directly control the speed of both motors, and to cross speed calibration of the motors to each other, so when the bot wants to go straight, it goes straight without veering off to one side.
What do you guys think?